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CHESTNUT TREE BLIGHT 



LETTER FROM THE 
SECRETARY OF AGRICULTURE 

TRANSMITTING 

IX RESPONSE TO SEXATE RESOLUTION 

OF APRIL 30, 1912, INFORMATION RELA- 
TIVE TO THE STUDY AXD INVESTIGA- 
TION OF THE SO-CALLED CHESTNUT 
TREE BLIGHT 




May 9, 1912.— Referred to the Committee on Agriculture and Forestry 
and ordered to be printed v.ith illustrations 



WASHINGTON 

1912 




n, At 

AUG 8 1912 



CHESTNUT TEEE BLIGHT. 



Department of Agriculture, 

Office of the Secretary, 

Washington, May S, 1912. 
The President of the Senate. 

Sir- In accordance with the resolution of the Senate, under date 
of April 30, directing that the Secretary of Agriculture "submit to 
the Senate, at the earliest practicable day, the results thus tar se- 
cured in the study and investigation of the so-called chestnut-tree 
blight, and the amount of money thus far expended m said study 
and investigation," I have the honor to report as follows: 

Observations on the disease known as the chestnut-tree blight, 
or the chestnut-bark disease, were begun in this department in the 
summer of 1907, as soon as any office was organized to do this class 
of work The results secured in the study and investigation oi this 
disease have been set forth in detail from time to time in the follow- 
ing publications, which are inclosed herewith, and constitute a part 
of this report: 

Bureau of Plant Industry Bulletin No. 121, Part VI, The Immunity of the Japanese 
Chestnut to the Bark Disease, February 10, 1908. 

Forest Service, unnumbered circular: Extent and Importance of the Chestnut 

B S£?3%I^fe^ 1 B^ No. 141, Part V, The Present Status of the < 'hest- 
nut Bark Disease, August 30, 1909. 

Farmers' Bulletin No. 467, The Control of the Chestnut Bark Disease, October 2b, 1911. 

A series of 34 photographs, mounted on 20 sheets, with explana- 
tory legends, illustrating various phases of the disease, are also 
appended, and constitute a part of this report. (Pis. I-XVl.) 

A summary of results follows': , . 

(1) The disease is caused by a parasitic fungus which kills the 
tree by girdling it at various points. Trees of all ages and condi- 
tions are attacked without discrimination. 

(2) A tree once attacked never recovers. It takes trom two 
months to four years to kill a tree, according to the size of the tree 
and the point of attack. The average length of life of a diseased 
tree is three years. Trees lulled by this disease sprout readily irom 
the trunks and roots, but the sprouts are in turn infected and lulled. 

(3) All species and varieties of chestnut now grown in this coun- 
try are subject to the disease, except the Japanese and Korean 
varieties, which are resistant. The Japanese and Korean chestnuts 
are small trees, fair nut producers, but probably valueless for tim- 
ber. No other species of trees have as yet been parasitized by the 
fungus, but it is not impossible that other species, such as oaks and 
walnuts, may later become attacked. 

(4) The disease is spread by the spores of the fungus, which are 
sticky in character. They are probably not diffused by wind to any 
appreciable extent, but are spread by rain, insects, probably also by 
birds, small mammals such as squirrels, and by man. Un barked 
timber and cordwood from diseased trees and diseased chestnut 



4 .CHESTNUT TREE BLIGHT. 

nursery stock may carry the disease bodily for great distances. The 
majority of infections take place through wounds made by bark- 
borers. The relation of insects to the disease appears to be very 
intimate. 

(5) The origin of the disease is unknown. Its obvious spread 
from a center — the vicinity of New York City — suggests that it is 
not a native disease; and the resistance of Asiatic species of chestnut 
to the disease suggests that it may have been imported from Asia 
with the Japanese chestnut. No evidence has been secured to 
connect the considerable losses of chestnut timber in the Southeastern 
States in past years with this disease; these losses were more probably 
due to attacks of insects. 

(6) The disease was first called to public attention in 1904, but 
it probably had already been present on Long Island for some years. 

(7) The value of the chestnut stand is variously estimated at 
between three hundred and four hundred million dollars. This 
disease has already caused an estimated minimum damage of 
$25,000,000. 

(8) Judging by the history of the disease to date, it may be expected 
to spread throughout the range of the chestnut tree during the next 
two years, unless checked by human effort. Whatever is done to 
control the disease by any methods known at present must be 
attempted immediately, else the disease will be beyond control by 
any effort ever likely to be put forth. 

(9) As shown on the accompanying map (PI. I) , the disease is now 
known to occur in at least 10 States, viz : Massachusetts, Rhode Island, 
Connecticut, New York, New Jersey, Pennsylvania, Delaware, Mary- 
land, West Virginia, and Virginia. In all of Connecticut, New Jersey, 
and Delaware, and in western Massachusetts, eastern New York, 
eastern Pennsylvania, and northeastern Maryland, the chestnut trees 
are already generally infected, and a large per cent are already dead. 

(10) Outside of this area of general infection the disease occurs at 
scattered points ("advance infections")- These consist mostly of 
single infected trees, or small groups of trees, often many miles apart. 

(11) Analogy with pear blight and peach yellows and with animal 
and human diseases that are controlled by destruction or isolation of 
the foci of infection suggests early destruction of the advance infec- 
tions as the only possible means of controlling the disease or limiting 
its range. There is no contagious disease known that does not yield 
to sanitation and quarantine. The destruction of diseased trees can 
not possibly be an effective means of control, however, in localities 
where the disease has already become general. 

This method of destroying advance infections has been employed 
extensively by private owners to check the progress of the disease 
in their own holdings. But since general cooperation is necessary 
to make any sanitation finally effective, it appears necessary to 
organize private effort under State control. This has already been 
done in Pennsylvania under special law, and is about to be done in 
Virginia under special law; and under the general laws now existing, 
in West Virginia and probably some other States. This department 
indorses the work of these States, and particularly the early and 
vigorous action of Pennsylvania. 

(12) Results to date indicate the following lines of activity as 
desirable and necessary to be carried out by this department and 
the various States in cooperation: 



CHESTNUT TREE BLIGHT. 5 

(a) The determining of the exact range of the disease, and the 
locating and cutting out of all advance infections. This work to be 
done in Virginia, West Virginia, western and probably southern Mary- 
land, Ohio, west (Mil Pennsylvania, central and western New York; 
possibly also in Kentucky, Tennessee, and North Carolina, following 
the methods now employed by the Chestnut Blight Commission of 
Pennsylvania. In all localities, and particularly in those States 
where no State quarantine of any sort is contemplated, it will be 
necessary to instruct private owners regarding the disease in order 
that they may take such measures as they see fit to protect their own 
property. 

(o) The careful inspection of all nurseries containing chestnut 
trees, and all chestnut nursery stock. 

(c) Determining by extensive local investigation the best methods 
of rapidly utilizing and marketing the timber of trees dying and dead 
from this disease, in order to protect timber owners against total 
loss, and to reduce infection. This work to be done in all localities 
where infection is already general. 

(</) Determining what changes in general forest management are 
necessary in those localities where the chestnut tree is already doomed, 
and so far as practicable putting such changes immediately into 
practice. 

(e) Continuing experiments on tree surgery and tree medication, 
in the hope of saving valuable orchard and ornamental trees. Any 
positive results from this line of work will also be applicable to other 
tree diseases, including those of fruit trees. 

(/) Continuing search for a resistant American stock, and breeding 
from resistant Asiatic stock, in order particularly to rehabilitate the 
chestnut-orchard industry ; at the same time breeding also for timber 
trees. Results of the greatest value to the chestnut-orchard industry 
can not fail to be secured from this line of work. 

(g) Making careful studies of the many unsolved scientific problems 
involved in the disease. Some of the more important of these are: 
The relation of the disease to climate; the relation of the parasite to 
the varying tannin content of the tree; the origin of the disease; the 
relation of birds and insects to the distribution of the disease; the 
nature and degree of resistance in the Asiatic varieties. 

(A) Determining in detail the relation of the disease to the future 
of the chestnut timber in the proposed Appalachian Forest Reserves, 
and making special effort to keep the disease out of this territory. 

With the exception of about $400, expended by the Forest Service 
in 190S in the work set forth in the inclosed circular by E. R. Hodson, 
all expenditures have been made in the Bureau of Plant Industry. 
The amount thus far expended in this study and investigation is 
$14,885.96 (estimated), which is itemized as follows: 

For the fiscal year ending June 30, 1908 (estimated) $350. 00 

For the fiscal year ending June 30, 1909 1, 365. 81 

For the fiscal year ending June 30, 1910 1 , 814. 27 

For the fiscal year ending June 30, 1 911 2, 210. 51 

For the fiscal year 1912, to date (estimated) 9, 145. 37 

Total 14. 885. 96 

I have the honor to be, sir, your obedient servant, 

James Wilson, Secretary. 



[Reprint of Bureau of Plant Industry Bulletin No. 121, Pt. VI, issued Feb. 10, 1908.] 

THE IMMUNITY OF THE JAPANESE CHESTNUT TO THE BARK 

DISEASE. 

By Haven Metcalf, Pathologist in Charge of the Laboratory of Forest Pathology. 



The Extent of the Bark Disease. 

Tho bark disease of the chestnut, caused by the fungus Diaporthe 
parasitica Murrill, has spread rapidly from Long Island, where it was 
first observed, and is now reported from Connecticut, Massachusetts, 
Vermont, New York as far north as Poughkeepsie, New Jersey, Penn- 
sylvania, and possibly Delaware. It is no exaggeration to say that it 
is at present the most threatening forest-tree disease in America. 
Unless something now unforeseen occurs to check its spread the com- 
plete destruction of the chestnut orchards and forests of the country, 
or at least of the Atlantic States, is only a question of a few years' time. 

An Immune Variety. 

Observations made by the writer during the past year indicate that 
all varieties and species of the genus Castanea are subject to the dis- 
ease except the Japanese varieties (Castanea crenata Sieb. and Zucc). 
AIL of the latter that have been observed in the field or tested by inocu- 
lations have been found immune. This fact can hardly fail to be of 
fundamental importance to the future of chestnut nut culture. 
Although the nuts are distinctly inferior in flavor to the European 
varieties, such as Paragon, the Japanese chestnut is already grown 
on a large scale as a nut-producing tree. There are, however, many 
trade varieties of dubious origin. Some of these may prove later to be 
subject to the disease. Immunity tests of all known varieties of chest- 
nuts have been undertaken. 

Attempts will also be made to hybridize the Japanese with American 
and European varieties, with the hope of combining the immunity of 
the former with the desirable qualities of the latter. 

However excellent as a nut and ornamental tree, the value of the 
Japanese chestnut as a forest tree is doubtful. It can be recom- 
mended only experimentally at present for forest planting. It cer- 
tainly will not take the place of the American chestnut. The tree is 
said to attain a height of 50 or 60 feet in Japan. As seen in this coun- 
try, it is a handsome tree, dwarfish and compact in habit, and rather 
slow growing. It has hardly had time to show how large it can grow. 

The immunity of the Japanese chestnut, together with the fact that 
it was first introduced and cultivated on Long Island and in the very 
locality from which the disease appears to have spread, suggests the 
interesting hypothesis that the disease was introduced from Japan. 
So far, however, no facts have been adduced to substantiate this view. 



[Reprint of Forest Service unnumbered circular, issued Oct. 21, 1908.] 

EXTENT AND IMPORTANCE OF THE CHESTNUT BARK 

DISEASE. 

By E. R. Hodson. 



Introduction. 



Three years ago a destructive fungous disease of the chestnut first 
attracted attention and almost immediately assumed the character 
of an epidemic. It seems to be one of the most serious diseases 
which has ever attacked an American forest tree, and has done great 
damage locally in and around New York City, and is now spreading 
rapidly in all directions to forest tracts in Connecticut, New York, 
New Jersey, and even into Pennsylvania. 

The disease was first studied by Dr. W. A. Murrill, of NewYork, 
and during the past 18 months it has been under investigation by 
Dr. Haven Metcalf, of the Bureau of Plant Industry. The tech- 
nical details given in this circular have been derived chiefly from the 
publications of the former and information supplied by the latter. 

Manner of Infection. 

The disease is caused by a fungus known as Diaporthe parasitica 
or Valsonectria parasitica, the spores of which enter the tree through 
wounds on branches or trunk. Dead twigs also offer a means of 
entrance, and there are probably other ways, not yet known, by 
which the trees become infected. 

From the point of entrance the fungus spreads in all directions 
throughout the cambium and inner bark until it completely girdles 
the branch or trunk it has attacked. It has been found that a few 
of the outer annual rings of the wood are also attacked, and it is very 
likely that the fungus penetrates some of the medullary rays in 
search of the food material which they contain; but the real seat of 
the injury is the inner bark and the growing layer of the wood. 

Symptoms. 

When a tree is first attacked the disease is not noticeable, and is 
likely to be overlooked. In many instances the trees are attacked 
first on the smaller branches. These are soon girdled, and the foliage 
turns yellow and then wilts. By these wilted branches the disease 
can be detected from a distance. The girdled branches or trees do not 
usually die until the second year, except when they are attacked 
very early in the season, or when the infected limbs are small. 

On limbs with smooth bark the diseased patches are sunken and 
discolored, with small brownish or yellow knobs scattered over the 

7 



8 CHESTNUT TREE BLIGHT. 

surface. On the edge of the affected area in the growing season 
there is a ring of greenish, yellowish, or bright yellow excrescences 
which resemble horns and are very conspicuous, so that in*young 
trees the disease is easily detected even before the branches wilt. In 
very dry weather, however, these horns may be nearly or entirely 
suppressed. Where the bark is thick, as on large trees, it is not 
changed in appearance, but the brownish knobs of the fruiting bodies 
show in the cracks, and the bark sounds hollow when struck. 

On account of its rapid action in killing or wilting small branches, 
the disease can not remain long undetected if the trees are under 
inspection. At the end of a single year the disease has usually made 
its presence conspicuous by a large number of dead and dying trees. 

Localities Affected. 

In 1905 the disease had already spread over a considerable area 
around New York City, where it apparently originated. In the 
present year it is spreading rapidly in a westerly direction over 
northern New Jersey, where in Morris County large tracts have 
recently been attacked. New York City is about the center of the 
infected area. Last year the chestnut tracts in Westchester and 
Nassau Counties in New York, Fairfield County in Connecticut, and 
Bergen County in New Jersey were severely attacked, and now Morris 
Essex, and Monmouth Counties, N. J., can be added. 

In Connecticut the disease is very severe at Stamford. It has been 
found near Danbury and Waterbury, and is known to extend along 
the coast to New London. It is also reported in southeastern Massa- 
chusetts and as far north as Wellesley. 

On Long Island it is common in the western part and along the 
northern shore to Huntington. It is likely that it occurs on the 
island wherever there is chestnut, although it has not yet been 
reported from the eastern end. It extends up the Hudson to Pough- 
keepsie, and across the river to the west; it has been found, though 
not in great abundance, at Turner and Warwick, and has been 
reported at Marlborough. Near the Connecticut line it occurs as 
far north as Pawling and is very destructive from Katonah all the 
way southward to New York City. 

In New Jersey the disease is very abundant in the northern and 
eastern parts, particularly near the coast in Bergen, Essex, and 
Monmouth Counties. Southward it is found along the Delaware 
River to Trenton, and abundantly along the coast near Chapel Hill 
and Eatontown in the northern part of Monmouth County. Recently 
a belt around Morristown and German Valley has become badly 
infected, and the disease has been discovered in wild trees at Newark 
and Fenton, Del., and at various points near Philadelphia, Pa. 
In Pennsylvania it is nowhere abundant yet, although it exists at 
Easton, South Bethlehem, and Morrisville, and is reported as far 
north as the Pocono Mountains and as far south now as Philadel- 
phia. It has also been found near Baltimore, Md., and in Bedford 
County, Va. 

The range at present, then, includes eight States: Connecticut, 
New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, 
and Massachusetts. Pennsylvania, so far as known, is not infected 
to any great extent, except in the eastern border, while Massachu- 
setts, Maryland, and Virginia arc touched only at one or two points. 



CHESTNUT TREE BLTG1IT. \) 

How the Disease Spreads. 

The yellow fruiting bodies so common on the diseased trees are 
constantly giving off millions of summer spores all through the grow- 
ing season. These are transported by various agencies to healthy 
trees, where they gain entrance through wounds in the bark. Wind 
is probably the principal agency, but the spores are no doubt carried 
by animals, birds, insects, and by shipment of infected material. 

The disease spreads locally through the gradual distribution of the 
spores from tree to tree, and at a distance chiefly through the ship- 
ment of infected material, such as nursery stock, bark, nuts, and 
other products. There is a possibility that long-distance infection is 
also effected by means of migratory birds. 

There are a number of facts which support the view that the wind 
has been the principal agency in spreading the disease over the pres- 
ent area. For instance, trees in open spaces exposed to w r inds, such as 
those along roads, at the edges of woods, or near streams or ponds, 
are apt to be infected sooner than the trees in more sheltered situations; 
trees on slopes or in depressions with diseased trees on higher ground 
near them usually become infected, evidently because they have been 
exposed to the wind-scattered spores from above; and in thinned 
stands, if the disease is present in the neighborhood, almost every 
chestnut becomes affected. In this instance the frequency of wounds 
is probably a large contributory cause. Dense woods, as a rule, act 
as a bar to the progress of the infection, except where the disease is 
very prevalent in the vicinity, in which case nothing seems to check 
its spread. 

Amount of Damage. 

The amount of loss caused by this disease is especially great, because 
it has developed in a region where the chestnut trees are extensively 
used for ornamental and park purposes. For this reason the losses 
have been acutely felt. There is, of course, no satisfactory basis for 
estimating the value of trees which are useful chiefly for aesthetic 
purposes, but the loss is certainly several million dollars. 

In Prospect Park, Brooklyn, there are but 6 chestnut trees left 
alive out of 1,400. In Forest Park, at Jamaica, Long Island, practi- 
cally all the chestnut trees are diseased and many are dead. The 
same applies to Bronx Park in New York City. In Nassau County, 
in western Long Island, few chestnut tracts have escaped serious dam- 
age. In Westchester County, N. Y., it is apparently only a question 
of a short time when nearly all the chestnuts will be destroyed. Many 
estates have sustained losses in scenic beauty which it is impossible to 
estimate. In the part of New Jersey adjacent to New York City the 
damage has been of the same character; parks and country estates 
have lost large number of fine chestnut trees which would not have 
been sold at any price. 

Although so far the injury to ornamental trees has attracted the 
most attention, the damage is not confined to these alone. Indeed, 
a far more serious phase of the epidemic is the menace to commercial 
forest tracts. Already many large tracts in at least five States have 
been attacked, and though great damage has been done in certain 
localities, it is very small compared with what it will be if the disease 
continues to spread. 



10 CHESTNUT TREE BLIGHT. 

A favorable feature in the situation is that so far the disease has 
done most damage in the vicinity of the sea, and there are some indi- 
cations that back from the sea, where there is less atmospheric moist- 
ure, it may be less virulent and may spread less rapidly. 

The damage which would result from the destruction or extensive 
depreciation of the commercial chestnut forests would be many times 
that from the loss of ornamental trees. Chestnut is one of the most 
rapidly growing and most useful of American forest trees, and it plays 
a very important part in the forests of the eastern United States. The 
wood is exceedingly durable and has, therefore, been extensively used 
for posts, poles, and railroad ties, while its grain, color, and ease of 
working give it a place among furniture and finishing woods. It is, 
moreover, a very vigorous sprouter and lends itself admirably to for- 
est management. With the exception of white pine, chestnut proba- 
bly makes the most profitable timber crop that can be grown in the 
northeastern part of the United States. 

UTILIZATION OF DEAD AND DISEASED TREES. 

Since the fungus does not work in the wood to any extent and ceases 
its activities when the tree is dead, the wood is not damaged as a 
result of the disease. In many cases only a part of the tree is affected, 
while the rest is healthy and can be utilized without difficulty. 

Dead trees are looked upon with suspicion, especially if they are 
killed by a disease, and the wood is popularly thought to be weaker 
than seasoned live timber. In the case of tins fungus there is no 
ground for such a prejudice; as a matter of fact, the dead material 
is fully as strong as any other timber if it is utilized within a few 
years, before the ordinary agencies of decay cause it to deteriorate. 

In most of the places where the disease prevails the problem of 
cutting and marketing small amounts is a difficult one. The dam- 
age from the disease is sudden, and it is often hard to find a market 
on short notice, especially for small quantities. 

In order to market the material, owners should encourage the con- 
tractors and pole buyers, who as a class are also vitally interested 
in the perpetuation of the chestnut, to go into sections where the 
disease is doing damage. Where the tracts are large enough or sev- 
eral are located close together, a portable sawmill might be put in. 
Where the quantity of chestnut is small, the best disposal is for ties, 
cord wood, and fence posts. Owners of small tracts where the disease 
has appeared can often cooperate to great advantage in order to 
find a market or make a lumbering operation possible. 

Measures of Prevention. 

The chestnut-bark disease is not like ordinary fungous diseases, 
which destroy a tree here and there after a number of years; it is even 
more virulent than the well-known pear blight, which it resembles 
in many particulars. It destroys quickly and spreads rapidly, and 
it is of the utmost importance to those who are interested in chestnut 
forests to secure a means of checking or stamping it out and of pre- 
venting its spread to localities which are as } 7 et unaffected. 

Seedlings and sprouts are attacked with equal virulence and old 
and young trees are killed alike. There is therefore no system of 



CHESTNUT TREE BLIGHT. 11 

forestry which can be used to control the disease. Two methods of 
checking its spread and lessening the source of the infection are 
available: 

1 . To cut out the diseased trees. 

2. To institute a quarantine against the shipment of infected 
material. 

In a forest tract the diseased trees should be cut outright — all 
trees which show the least sign of infection should be removed. In 
other situations, where the trees have a peculiar value, it may be pos- 
sible to save them by cutting off the diseased parts only; but if the 
trunk of a tree is attacked, the whole tree, no matter how valuable it 
is, should be cut at once, for it is practically useless to try to save it. 

Since the disease generally spreads less rapidly in dense stands than 
in thin ones, it will often be possible, by close inspection and the 
prompt removal of infected trees, to stamp out the disease altogether 
from a forest tract. For the same reason, however, if many diseased 
trees are to be removed and their removal would make the stand 
very open, it will often be better to make a clean cut of all the chestnut. 

All diseased bark should be removed and burned. After that is 
done the wood is practically free from infection and can be used or 
stored with safety. 

Even greater effort should be directed toward preventing the 
spread of the disease to localities winch are as yet unaffected than 
to stamping it out in places where it already has a firm hold. 

For this reason definite legislation seems necessary, and it is very 
desirable thafc each State concerned should enact a law providing for 
a quarantine against infected chestnut products, chiefly nursery 
stock. The law should also provide for systematic and thorough 
inspection of the disease and require the cutting out of infected trees 
wherever they are a menace to healthy stands of chestnut. 

The nature of the disease and the necessity of fighting it should 
be made known to the people throughout the region affected by 
means of the press and by enlisting the aid of the granges and other 
< organizations interested . 

It is to be hoped that some natural limitation to the destructive- 
ness of the disease may be found and that it may be checked by 
natural causes. But its rapid spread and its great virulence make 
waiting dangerous. Prompt and energetic measures should be 
taken to stamp it out wherever it appears. 



[Reprint of Bureau of Plant Industry Bulletin No. 141, Pt. V, Issued Aug. 30, 1909.] 

THE PRESENT STATUS OF THE CHESTNUT BARK DISEASE. 

By Haven Metcalf, Pathologist, in Charge, and J. Franklin Collins, Special Agent, 
Investigations in Forest Pathology. 



History of the Chestnut Bark Disease. 

In 1904 Mr. H. W. Merkel, of the New York Zoological Park, 
observed a disease which was destroying large numbers of chestnut 
trees in the city of New York. This disease is what is now known 
as the chestnut bark disease. Even at that time it is certain that it 
had spread over Nassau County and Greater New York, and had 
found lodgment in the adjacent counties of Connecticut and New 
Jersey. No earlier observation than this is recorded, but it is evident 
that the disease, which would of necessity have made slow advance 
at first, must have been in this general locality for a number of years 
in order to have gained such a foothold by 1904. Conspicuous as it 
is, it is strange that the fungus causing this disease was not observed 
or collected by any mycologist until May, 1905, when specimens were 
received from New Jersey by Mrs. F. W. Patterson, the Mycologist 
of the Bureau of Plant Industry. In the same year Dr. W. A. 
Murrill began his studies of the disease, publishing the results in the 
summer of 1906. By August, 1907, specimens received by this 
bureau showed that the disease had reached at least as far south as 
Trenton, N. J., and as far nortli as Poughkeepsie, N. Y., and was 
spread generally over Westchester and Nassau Counties, N. Y., Bergen 
County, N. J., and Fairfield County, Conn. 

Present Distribution. 

The present distribution of the chestnut bark disease is shown on 
the accompanying map (fig. 1). By this it will be seen that infec- 
tion is now complete in the general vicinity of the city of New York. 
Outside of this area the disease already occurs at scattering points 
in a number of States. In every case its occurrence has been defi- 
nitely authenticated by specimens which have been examined micro- 
scopically. Reports have been received indicating that the disease 
is found at many other places, but not being substantiated by 
specimens these localities have not been shown on the accompanying 
map. It is only fair to state, however, that such reports have been 
received from points as remote as Cape Cod, Wellesley, and Pitts- 
field, Mass.; Rochester and Shelter Island, N. Y., and Akron, Ohio. 

The bark disease is entirely different from a disease which during 

the past 20 years has caused the death of many chestnut trees on 

the Atlantic slope, particularly south of the Potomac River. The 

latter disease, which is now being studied by the Department of 

12 



CHESTNUT TltEE BLIGHT. 



13 



Agriculture, is associated with insects, is much slower in action than 
the bark disease, and produces a stag-headed condition of the tree. 
It can be quite confidently stated that the bark disease does nol yet 
occur south of Virginia and at only a few points in that State. 

Investigations are in progress to determine the origin of the bark 
disease in America and the details regarding its spread. The theory 
advanced in a previous publication of this bureau, 1 that the Japanese 
chestnuts were the original source of infection, has been strengthened 
by many facts. It yet lacks much of demonstration, however, and is 
still advanced only tentatively. 

While the disease has spread principally from the vicinity of New 
York there is much to indicate that it occurred at other points at an 
early date. Chester's Cytospora on a Japanese chestnut, noted at 
Newark, Del., in 1902, 
may have been the bark 
disease. Observations 
by the junior writer in- 
dicate that this disease 
may have been present 
in an orchard in Bedford 
County, Va., as early as 
1903, and that in Lan- 
caster County, Pa., it 
probably was present as 
early as 1905. All other 
points shown on the 
map outside of the area 
of general infection ap- 
pear to have been in- 
fected only within one 
or two years. 

The bark disease ap- 
pears practically to ex- 
terminate the trees in 
any locality winch it in- 
fests. A survey of For- 
est Park, Brooklyn, 
showed "that 16,695 
chestnut trees were 
killed in the 350 acres of 
woodland in tins park alone. Of tins number about 9,000 were 
between 8 and 12 inches in diameter, and the remaining 7,000 or 
more were of larger size." 

In a recent publication Dr. W. A. MurriU estimates the financial 
loss from this disease "in and about New York City" at "between 
five and ten million dollars." The aggregate loss throughout the 
whole area of country affected must be much greater. 

The bark disease occurs on both chestnut and chinquapin, regard- 
less of age, origin, or condition. It does not occur on any other tree 
so far as known. All reports of its occurrence on the chestnut oak 
(Quercus prinus) have proved to be unfounded. It is not yet known 
whether the goldewleaf chinquapin of the Pacific coast (Castanopsis 
ehrysophylla) is subject to this disease. 




Fig. 1.— Map of the eastern portion of the United States, showing 
the distribution of the chestnut bark disease. The heavily 
shaded part shows the counties wherein infection is already 
complete. The round dots show other points W'hero the disease 
is positively known to occur. 



i Bureau of Plant Industry, U. S. Department of Agriculture, Bulletin 121, Pt. VI. 1908. 



14 CHESTNUT TREE BLIGHT. 

According to Sudworth, the range of the native chestnut is "from 
southern Maine to northwestern Vermont (Winooski River), southern 
Ontario, and southern shores of Lake Ontario to southeastern Mich- 
igan; southward to Delaware and southeastern Indiana, and on the 
Allegheny Mountains to central Kentucky and Tennessee, central 
Alabama, and Mississippi." The range of the chinquapin is "from 
southern Pennsylvania (Adams, York, Franklin, and Cumberland 
counties) to northern Florida and eastern Texas (Neches River)." 
The bark disease may, therefore, be expected to occur at any point 
within these limits, as well as in any other localities where the chest- 
nut is grown as an ornamental or orchard tree. 

Cause and Symptoms. 

The disease is caused by the fungus Diaporthe parasitica Murrill 
(also known as Valsonectria parasitica (Murrill) Renm). The spores 
of this fungus, brought by some means from a previously diseased 
tree, enter the bark through wounds; possibly also in other ways. 
The leaves and green twigs are not directly affected. From the 
point of infection the fungus grows in all directions through the inner 
bark until the growth meets on the opposite side of the trunk or limb, 
which in this way is girdled. The wood is but little affected. Limbs 
with smooth bark attacked by the fungus soon show dead, discolored, 
sunken patches of bark covered more or less thickly with the yellow, 
orange, or reddish-brown pustules of the fruiting fungus. In damp 
weather or in damp situations the spores are extruded in the form of 
long irregular "horns," or strings, at first greenish to bright yellow 
in color, becoming darker with age. Plate XVII, figure 3 , shows a part 
of a branch of a diseased chestnut tree magnified 3^ diameters. In 
this illustration the typical appearance of the pustules in damp 
weather and the projection of the spores of the fungus in the form 
of "horns," or threads, are shown. These threads may be especially 
conspicuous near the edges of diseased areas. If the spot is on the 
trunk or a large limb with very thick bark there is no obvious change 
in the appearance of the bark itself, but the pustules of the fungus 
show in the cracks of the bark and, on account of the destruction of 
the layers beneath, the bark often sounds hollow when tapped. A 
patch usually grows fast enough to girdle the branch or trunk that 
it is on during the first summer. 

The damage may not be immediately apparent, since the water 
supply from the roots continues to pass up through the compara- 
tively uninjured wood to the leaves, but when in the following spring 
the new leaves are put out they are usually stunted and soon wither. 
The appearance of such trees is very characteristic. Plate XVII, fig- 
ure 1, shows large chestnut trees killed by the bark disease. In this 
illustration the trees to the left show the characteristic stunted foliage, 
which indicates that they were girdled during the previous year, 
while the tree on the right having no foliage was presumably girdled 
by the fungus at least two summers before the photograph reproduced 
was taken. Plate XVII, figure 2, shows an orchard tree with recently 
girdled branches. Nothing else except an actual mechanical injury — 
breaking off of trunk or limb — produces such an effect as is shown in 
these illustrations. The imperfectly developed leaves often persist on 
the dead branches throughout the summer. 



CHESTNUT TREE BLIGHT. 15 

The great damage which the disease has done thus becomes most, 
apparent in the last week of May or the first week in Juno, giving 
rise to th< v ('also but common idea that the fungus does its work at 
this time of the year, when in reality the harm is done during the 
previous summer. If the first attack is on the trunk, of course the 
entire tree dies. If, on the other hand, the small branches are first 
involved, the tree may live for several years. 

It is very easy for a person not familiar with fungi to confuse this 
parasite with various other fungi which occur commonly on the dead 
wood of chestnut and other trees, such as species belonging to the 
genera Calocera, Cytospora, and Cytosporina. The superficial re- 
semblance is sometimes very strong, but a microscopical examination 
instantly reveals the true nature of the organism in question. On 
account of tins common confusion no dependable diagnosis of the 
bark disease can be made in a new locality without a microscopical 
examination of specimens by an expert. 

Restriction of Spread. 

how the further spread of the bark disease may be limited. 

By the Inspection of Diseased Nursery Stock. 

It becomes more and more evident as this disease is studied that 
diseased nursery stock is the most important factor in its spread to 
distant points. In that part of the country where it is already well 
established in the native chestnuts its progress is rapid and sure, but 
there is no evidence at present that it is able to pass to remote dis- 
tricts, tens or hundreds of miles away, except on diseased nursery 
stock. Of course it is conceivable that the spores are carried by 
birds. Such distribution would, however, follow in general the great 
lines of bird migration north and south and hence would not be an 
important factor in the western spread, except locally. During the 
summer of 1908 nearly every chestnut nursery and orchard of impor- 
tance in the Atlantic States north of North Carolina was visited, and 
very few were found free from the bark disease. Several cases were 
observed where the disease had obviously spread from the nursery 
to adjacent wild trees. This is the only way in which the disease is 
likely to spread beyond the Alleghenies. 

It is therefore obvious that every State in which the chestnut or 
chinquapin grows should as speedily as possible pass a law putting 
the chestnut-bark disease on the same footing as other pernicious dis- 
eases and insect pests, such as the San Jose scale, against which quar- 
antine measures are taken. The Department of Argiculture will be 
glad to give detailed suggestions or advice regarding the framing of 
such laws. Inspectors who already have legal power to quarantine 
against this disease should now take special care that no shipment of 
chestnut stock escapes their rigid inspection. 

A campaign of education should also be undertaken by patholo- 
gists and inspectors in every State in order to acquaint the public 
with the nature and appearance of the bark disease, so that it may 
be quickly recognized and stamped out in any particular locality in 
which it appears. The Department of Agriculture will cooperate in 
the following ways: Specimens from suspected trees sent in by any 



16 CHESTNUT TREE BLIGHT. 

person will be promptly examined and the presence or absence of the 
disease reported. Typical specimens showing the disease (with the 
fungus previously killed by soaking in formalin to insure against any 
infection from this source) will be sent upon application to any inspec- 
tor, forester, pathologist, or other State or experiment station officer, 
to any nurseryman or orchardist growing chestnuts, or to any botanist 
or teacher of botany. So far as the supply permits lantern slides 
and photographs will, upon application, be loaned for special lec- 
tures, exhibits, etc., to the officers of States, experiment stations, or 
colleges. By these means the inspectors first, and then the general 
public, may become familiar with the appearance and work of the 
disease in localities that it has not yet reached, and when it does ap- 
pear may be able to recognize it before it is too late to take efficient 
measures against it. 

Although its present distribution is that shown by the map (fig. 1), 
the bark disease may be confidently looked for in any orchard or 
nursery in the United States that contains chestnut trees. All such 
places should therefore be rigidly inspected at the earliest possible 
date. 

By the Prompt Destruction of Diseased Trees. 

When the bark disease is first noticed in any locality all the 
affected trees should be immediately cut down unless, as in the case 
of orchard and some few ornamental trees, they are of sufficient 
individual value to warrant special treatment. Diseased trees if 
untreated are doomed to death in any case. If permitted to stand, 
every such tree becomes a center of infection, certain to spread the 
disease to all neighboring trees, and so long as it will soon die if left 
to itself the sooner it is cut down the better. 

When cut, the brush should be immediately gathered and burned 
in order to destroy the fungus in the bark. Whenever the bark is 
removed from the trunk — as, for example, when the trees are to be used 
for poles — it should be immediately burned with the brush. Even 
when the tree is to be used for firewood an effort should be made to 
cut off at least all the diseased patches of bark on the trunk and 
large limbs when the tree is cut and to burn this bark along with the 
brush; otherwise the brush and the piled wood will continue to 
spread infection, since it has been found that the fungus continues 
alive on dead bark for at least six months after cutting. 

Sprouts arising from the stumps of cut trees will be free from the 
disease for the first year at least, but must then be carefully inspected 
to be sure that no infection has persisted. 

By the Treatment of Diseased Treks. 

During the past two years the Office of Investigations in Forest 
Pathology has been conducting certain experiments and collecting 
information in regard to the best methods of treating diseased trees. 

At present it is impossible definitely to record general beneficial 
results from any of the sprayings which have been undertaken or have 
been under observation. This may in part be due to the fact that it is 
vet too early to judge satisfactorily all the results and in part, per- 
haps, to the infrequency of sprayings. 



CHESTNUT TREE BLIGHT. 17 

Observations and experiments seem to bear out the statement that 
it is very improbable thai any method of spraying can interfere with 
the growth of the fungus if it has once established itself in the inner 
bark, but it may be of considerable importance in preventing the 
development of spores which come from other trees or from other 
parts of the same tree. 

It has already been demonstrated that the crotches of branches 
and enlarged bases of sprouts are very susceptible to infection because 
they are favorable places for the lodgment of water, dust, spores, etc. 
In a large majority of cases infections are definitely known to ha^'e 
originated at a point where the outer bark had been injured in some 
way, leaving the inner living bark exposed, or where the entire bark 
over a more or less limited area had been stripped from the tree or 
cracked and split away from the wood. Certain injuries which are 
known to have afforded entrance for the disease have been of such a 
nature that they might easily be overlooked, while others have been 
quite obvious, even to the careless observer. Among the latter may 
be mentioned broken limbs, split limbs, branches which have been 
carefully cut but not properly treated with tar or paint, bruises from 
hames, plows, and cultivators; also poor grafts and diseased grafting 
scions. Among the former may be included bruises from boot heels, 
climbing spurs, holes made by borers and other insects, knife and 
saw cuts, and frost cracks. 

Almost the only treatment that can at present be safely recom- 
mended as surely retarding the spread of the disease to a greater or 
less extent is one which will never be of practical use except in the 
case of orchard trees or certain valuable ornamental trees. It consists 
essentially in cutting out the infected branches or areas of bark and 
carefully protecting the cut surfaces from outside infection by means 
of a coat of paint or tar. This cutting must be thoroughly done and 
the bark of every infected place entirely removed for a distance of at 
least an inch (where the size of the branch permits) beyond the 
characteristic, often fan-shaped, discolored areas produced by the 
growing fungus in the inner bark. All small infected twigs or 
branches should be cut from the tree, the cut being made well back 
of the diseased area. A pruning knife with an incurved tip, a hollow 
gouge, or any other clean-cutting instrument will serve for cutting 
out diseased spots." So far as the exigencies of the case will permit, 
all borers' holes should be cut out. It has been repeatedly observed 
in the field that infection often starts where borers are at work, or 
even at the old holes made by them. The paint or tar may be applied 
by means of a good-sized brush, care being taken to cover every part 
of the cutting. Treatment, should begin, or observations at least, at 
the base of the tree and the fact ascertained whether the disease has 
already girdled the trunk. If such is the case it will be a waste of 
time to attempt any treatment; instead, cut the tree down at once., 
A rigid watch must be kept, especially during the growing season, for 
new infections or infections which were overlooked in the earlier 
examinations, and if any are observed they must be treated promptly 
as above mentioned. Constant vigilance is necessary to Keep the 
disease in check. It is suggested that examinations be made about 
June 1, July 15, and September 1. During a very rainy or foggy 
season, when conditions are particularly favorable for the growth of 
fungi, it may be advisable to inspect as often as once a month. 
43017°— S. Doc. 653, 62-2 2 



18 CHESTNUT TREE BLIGHT. 

Iii regions in which the disease is so widespread that almost every 
tree is infected, as, for instance, within 25 miles of the city of New 
York, it is extremely doubtful whether any individual treatment will 
pay. Under such conditions immediate reinfection is almost sure to 
occur at one or more of the small unnoticed abrasions or injuries 
which are quite certain to exist on most trees. In a region, however, 
where only isolated cases have yet appeared it is quite possible to 
stamp out the disease, or at least to prevent its rapid spread, by 
promptly cutting out and carefully burning all diseased bark and 
limbs, thus destroying these new sources of infection. If a tree is 
too badly infected to be worth treating it should not be left standing, 
for it will then become a continual menace to all surrounding chest- 
nuts. 

The Office of Investigations in Forest Pathology asks the cooper- 
ation of all persons who have observed the disease or experimented 
with it in any way. If such people will send in an early report of the 
kind of treatment used, time of treatment, methods employed, and 
results obtained (even if adverse), it may be possible to arrive at an 
earlier and more definite conclusion in regard to the possibilities or 
impossibilities of control than would otherwise be the case. 

Conclusions. 

It is to be hoped that in the economy of nature some limiting fac- 
tor will arise to check the spread of the bark disease before it has 
wrought the same destruction throughout the country that it already 
has in the vicinity of New York. But at present there is nothing in 
sight that promises even remotely to check its spread into new terri- 
tory except the general adoption of the measures advocated in these 
pages. It can not be argued that because of its apparently recent ori- 
gin and rapid spread it will soon disappear of itself. Such diseases as 
pear blight and peach yellows have been in the country for more than 
a century and yet show no sign of abating except when actively 
combated by modern quarantine methods. Nor can any conclusions 
be drawn from the fact that chestnuts in the Southern States have 
suffered from a disease during the past twenty years, since, as already 
stated, that is a totally different thing from the bark disease. 

Where the bark disease is already firmly established and has 
attacked 50 per cent or more of the chestnut trees, as in the vicinity 
of the city of New York, it is probably too late to try to do anything, 
but where the disease is just appearing there is no reason to doubt that 
strict quarantine methods will apply as well to this as to any other 
disease, whether of plants or animals. The question to settle is sim- 

{)ly which is more costly — to use the methods recommended or to 
ose the trees. The people concerned must decide. 



[Reprint of Fanners' Bulletin No. 467, issued Oct. 28, 1911.] 

THE CONTROL OF THE CHESTNUT BARK DISEASE. 

By Haven Metcalf and J. Franklin Collins. 



The Disease. 
history and distribution. 

The chestnut bark disease was first recognized as a serious disease 
in the \icinity of New York City in 1904, and the first* publication 
regarding it appeared in 1906. There is reliable evidence, however, 
that it was present on Long Island at least as early as 1893. Its 
origin is unknown, but there is some evidence that it was imported 
from the Orient with the Japanese chestnut. • This view is not, how- 
ever, held by all investigators. But whatever may have been its time 
or place of origin, it is certain that it has now spread into at least 
10 States, as is shown by the accompanying map (fig. 2). In the 
vicinity of New York City and through adjacent counties it has 
killed practically all chestnut trees. Throughout a much larger 
neighboring area, as shown in figure 2, practically all chestnut trees 
are infected. Outside of this area, throughout the countiy from the 
northern border of Massachusetts and from Saratoga County, N. Y., 
to the western border of Pennsylvania and the southern border of 
Virginia, scattering areas of infection are known to occur and may 
be expected at any point. 

So far as is now known, the bark disease is limited to the true 
chestnuts — that is, to the members of the genus Castanea. The 
American chestnut, the chinquapin, and the cultivated varieties of 
the European chestnut are all readily subject to the disease. Only 
the Japanese and perhaps other east Asian varieties appear to have 
resistance. In spite of popular reports to the contrary, it can be quite 
positively stated that the bark disease is not now known to occur on 
living oaks, horse-chestnuts, beeches, hickories, or the golden-leaf 
chinquapin (Castanopsis chrysophyUa) of the Pacific coast. 

FINANCIAL LOSSES. 

The bark disease appears ultimately to exterminate the chestnut 
trees in any locality which it infests. A survey of Forest Park 
(Brooklyn) showed "that 16,695 chestnut trees were killed in the 
350 acres of woodland in this park alone. Of this number, about 
9,000 were between 8 and 12 inches in diameter, and the remaining 
7,000 or more were of larger size." Three years ago the financial loss 
from this disease "in and about New York City" was estimated at 
"between five and ten million dollars." 

19 



20 



CHESTNUT TREE BLIGHT. 



The writers regard $25,000,000 as a conservative estimate of the 
financial loss from this disease up to 1911. In many localities the 
greatest damage has been among chestnuts grown for ornamental 
purposes, which have a value greatly in excess of their value as lumber. 
Depression in the value of real estate, especially suburban or near- 
suburban, owing to the death of the chestnut trees, must be taken 
into account in an estimate of this kind, as well as the loss of the 
trees themselves. 




Fig. 2.— Map of (ho northeastern part of Hie United States, showing the distribution of I ho chestnut bark 
disease. The horizontally lined part shows the approximate area wherein the majority of chestnut trees 
are already dead from the bark disease. The part marked by vertical lines shows the approximate area 
wherein infection is already complete. The round dots show the location of advance infections of the 
disease. Many of these have already been eradicated. The map has been compiled from both obs srva- 
tions and correspondence. The writers are under especial obligations to Dr. Perley Spanlding, Prof. A. 
H. Graves, Mr. I. C. Williams, Mr. W. H. Rankin, Mr. J. F. O'Byrne, Mr. F. W. Besley, Dr. Ernest S. 
Reynolds, and Mr. II. (i. MacMillan, for data along this line. According to Dr. G. P. Clinton (Connect- 
icut Agricultural Experiment Station, Report of the Botanist, 1909 and 1910) there are many more 
points of infection in Connecticut than are shown on this map. 

Cause and Symptoms. 

The chestnut bark disease is caused by a fungus parasite known 
under the technical name of Diaportlie 'parasitica Murrill. ^'hen 
any of the microscopic spores (reproductive cells) of this fungus gain 
entrance into any part of the trunk or limbs of a chestnut tree they 
give rise to a spreading "sore" or lesion, which soon girdles the tree. 
If the part attacked happens to be the trunk, the whole tree in con- 
sequence is killed, perhaps in a single season. If the smaller branches 
are attacked, only those branches are killed, or only those portions of 






CHESTNUT TREE BLIGHT. 21 

branch cvs beyond the point of attack, and the remainder of the tree 
may survive for several years (fig. 3). 

Some of the symptoms are quite prominent. Limbs with smooth 
bark attacked by the fungus soon show dead, somewhat discolored, 
sunken areas (occasionally with a raised margin), which continue to 
enlarge and soon become covered more or less thickly with yellow, 
orange, or reddish-brown spots about the size of a pinhead. These 
spots are the pustules of the fruiting fungus. In damp weather or 
in damp situations, masses of summer spores are extruded in the 
form of long, irregularly twisted strings or "horns," which are at first 
bright yellow to greenish yellow or even buff, becoming darker with age 
(PI. XVII, fig. 3). If the lesion is on the trunk or a large limb with 
very thick bark, there is no obvious change in the appearance of the 
bark itself, but the pustules show in the cracks and the bark often 
sounds hollow when tapped. After smooth-barked limbs or trunks 
are girdled the fungus continues to grow extensively through the 
bark, sometimes covering the entire surface with reddish-brown 




Fig. 3.— Large chestnut tree partly killed by the bark disease. Note the sprouts with leaves near the top, 
the dwarfed leaves on the lower right-hand limb, and the healthy lower branches with leaves. 

pustules (fig. 4). These pustules produce mostly winter spores 
(ascospores), although occasionally the long strings of summer spores 
(PI. XVII, fig. 3) are also produced, even on bark that has been 
dead at least a year. 

After a branch or trunk is girdled, the leaves change color and 
sooner or later wither. Such branches have a very characteristic 
appearance and can hardly be mistaken for anything else, except in 
certain localities where the work of twig-girdling insects may pro- 
duce a similar appearance in the spring. In case the girdling by 
the fungus is completed late in the season, the leaves of the follow- 
ing spring assume a yellowish or pale appearance and do not develop 
to their full size (fig. 3). If the girdling is completed between spring 
and midsummer the leaves may attain their full size and then turn 
a somewhat characteristic reddish-brown color, which can easily be 
detected at a long distance. Later this leaf coloration changes to 
a more brownish tinge and the leaves are commonly persistent for a 
considerable time. The chestnut fruits (burs) on a spring-girdled 



22 



CHESTNUT TREE BLIGHT. 



branch may or may not attain full size, according to whether the 
girdling by the disease was completed late or early in the spring. 
These burs commonly persist on the tree during the following win- 
ter, thus producing the only symptom which is at all conspicuous 
during the leafless season. The great damage which the disease has 
done in the late summer thus becomes most evident at the beginning 
of the next season, and that done in the spring becomes evident later 
in the same season, giving rise to the false but common idea that 
the fungus does its work at the time of year that the leaves change 
color, when in reality the harm was done much earlier. 




■ 













Fig. 4.— Dead chestnut bark showing pustules of the parasitic fungus bearing winter spores. 

Perhaps the most easily seen as well as the longest persist en ( 
symptom of the bark disease is the prompt development of sprouts, 
or "suckers," on the trunk of the tree (fig. 3) and at its base, or 
somewhat less frequently on the smaller branches. Sprouts may 
appear below every girdling lesion on a tree, and there are usually 
many such lesions. These sprouts are usually very luxuriant and 
quick growing, but rarely survive the second or third year, as they 
in turn are killed by the fungus. The age of the oldest living sprout, 
as determined by the number of its annual rings, is an indication of 
the minimum age of that portion of the infection immediately above 



CHESTNUT TREE BLIGHT. 23 

it. Sprouts are sometimes produced as a result of other injuries; 
for instance, trees girdled by borers may develop sprouts, but these 
are generally less rapid in growth and are distributed with greater 
uniformity over the trunk. 

MEANS OF SPREAD AND ENTRANCE. 

The disease is spread by the spores of the fungus, of which there 
are two kinds. As both kinds of spores appear to be sticky, there 
is no evidence that they are transmitted by wind except where they 
may be washed down into the dust and so blown about with the 
dust. The sport's are spread easily through short distances by rain; 

fmrticularly they are washed down from twig infections to the 
o'wer parts of the tree. There is strong evidence that the spores 
are spread extensively by birds, especially woodpeckers, and there 
is also excellent evidence that they are spread by insects and by 
various rodents, such as squirrels. The disease is carried bodily for 
considerable distances in tan bark and unbarked timber derived from 
diseased trees. One of the most prolific sources of general infection 
has been the transportation of diseased chestnut nursery stock from 
infected to uninfected localities. 

When the spores have once been carried to a healthy tree, they 
may develop in any sort of hole in the bark which is reasonably moist. 
These may be wounds or mechanical injuries, but by far the most 
common place of infection is a tunnel made by a borer. Borers' 
tunnels are moist, even in dry weather, and in them the spore finds 
surroundings favorable to its development. In many parts of the 
country where the disease is prevalent there is very direct evidence 
that bark borers, and particularly the two-lined chestnut borer 
(Agrilus bilineatus), are directly associated in this way with 90 
per cent or more of all cases of this disease. We are informed that 
the Bureau of Entomology will issue a circular on the insects asso- 
ciated with the chestnut bark disease. 

The writers have no definite evidence, experimental or other- 
wise, to show that a tree with reduced vitality is more susceptible 
to infection, or that the disease spreads more rapidly in such a 
tree, than in a perfectly healthy and well-nourished tree of either 
seedling or coppice growth, provided that such reduced vitality 
does not result in or is not accompanied by bark injuries through 
which spores can gain entrance. 

The Control of the Disease. 

elimination and quarantine. 

Fundamental Observations and Experiments. 

No method of immunizing individual trees against the bark dis- 
ease is yet known, and no method of treating or curing them when 
once attacked is certain in its results. While this is unfortunate 
from the standpoint of the owner of orchard trees and large orna- 
mental trees of great individual value, no method of dealing with 
single trees — surgery, medication, spraying, etc. — however successful 
in itself, would meet the demands of the present situation. It is not 



24 CHESTNUT TREE BLiGHT. 

practicable at present to apply an}^ individual method of treatment 
to forest trees; the individual tree is not worth it, and will not be 
for many years. Therefore, so far as the chestnut forests are con- 
cerned, we do not need to regret particularly that no individual 
treatment has yet been discovered that is entirely effective. 

Fortunately, however, there is a method of dealing with the situa- 
tion which is applicable to the country as a whole and which, so 
far as tested, is practicable. Early in the course of the writers' 
investigations it became evident that the disease advances but slowly 
in a solid line, but instead spreads from isolated centers of infec- 
tion, often many miles in advance of the main line of disease. That 
such is the case is evident from a glance at figure 2. It therefore 
seemed probable that if these advance infections could be located 
at a reasonably early stage they could be eliminated at relatively 
little expense, thus preventing further spread from these points at 
least. Accordingly, the country within approximately 35 miles 
of Washington, D. C, was chosen in the fall of 1908 as preliminary 
territory in which to test this method of control. This section has 
since been gone over fairly thoroughly once a year. As will be seen 
by figure 2, 14 points of infection were located, and the infected 
trees destroyed. Most of this work was done by the senior writer. 
The largest infection was a group of nursery trees that had been 
imported from New Jersey; the smallest, a single lesion on a small 
branch of a large forest tree. In one case 11 forest trees in a group 
were infected, the original infection having been two trees, dating 
apparently from as early as 1907. Up to the present time (June, 
1911) the disease has not reappeared at any point where eliminated 
and the country within a radius of approximately 35 miles from 
Washington is apparently free from the bark disease, although new 
infections must be looked for as long as the disease remains elsewhere 
unchecked. It is therefore believed that this method of attack will 
prove equally practicable in other localities, and if carried out on a 
large scale will result ultimately in the control of the bark disease. 

Legal Considerations. 

In carrying such a scheme of control into effect on a large scale, 
however, legal difficulties are at once encountered. The bark dis- 
ease threatens the extinction of the chestnut throughout its range. 
As it has already been found in at least 10 States and the District of 
Columbia, it is essentially a national issue, but there is no law 
whereby the Federal Government can attempt to cope with the 
emergency. Each State must act on its own initiative and control 
the disease or let it go as its officers and legislative bodies see fit. 
Herein lies one of the most serious aspects of the matter; for if one 
State elects to undertake control of the disease it will be seriously 
handicapped if neighboring States do not. Any method of elimina- 
tion, isolation, or quarantine in dealing with any disease of plants, 
domestic animals, or human beings necessitates general cooperation. 
It is not practicable to try to control the bark disease solely by the 
cooperation of individual owners of chestnut woodland, since a sin- 
gle indifferent or obstinate person can nullify the efforts of an entire 
community. The control of the chestnut bark disease must there- 
fore be undertaken by the separate States under special legislation. 



CHESTNUT TREE BLIGHT. 25 

Possibly in certain States the crop and woodland pest laws, which 
ordinarily apply only to nursery stock, may be broad enough to 
include this disease, but in most States the first thing to be done 
is to obtain the necessary legal authority and an appropriation for 
action along the following lines, as has already been done in Penn- 
sylvania. 

The Method in Detail. 

Locating advance infections ("scouting"). — The first thing to 
be done in each State is to determine the exact range of the disease 
in that State, and particularly to locate the advance points of infec- 
tion. This is by far the most difficult feature of the entire pro- 
gram, because the work must be directed and in large measure car- 
ried out by experts; otherwise diseased trees will be left, and the re- 
sults can not be depended upon. It is best intrusted to professional 
plant pathologists, or at least to botanists familiar with fungi and 
the collecting of fungi, and even these must have some preliminary 
knowledge of this particular disease. The symptoms of the disease 
are too obscure and the means of locating it too intricate to make it 
possible for a person without a professional knowledge of plant dis- 
eases to deal successfully with the situation, no matter how well in- 
formed in agriculture or forestry or how experienced in the care of 
trees. It is suggested that in most States this part of the work 
would be best handled by the pathologists of the State agricultural 
experiment stations. 

For assistants the pathologists having this work in charge should 
choose the best scientific observers obtainable, regardless of other con- 
siderations, but persons with some knowledge of plant pathology are 
to be preferred. College students trained in these lines are usually 
available, for the summer vacation at least, and make in many 
respects the most desirable ''scouts" for this work. But all "scouts" 
must be carefully and individually trained by the expert in charge. 

Attention should first be directed to the advance spots of infection 
already known to exist, and when found the diseased trees should be 
destroyed or marked for destruction. No difficulty will be experi- 
enced in locating infections 2 years old or more, but the greatest diffi- 
culty will be met in locating infections of the current year. Every 
tree in the immediate vicinity of older infected trees must be carefully 
gone over. Many dubious cases will be found, and from such trees 
samples of the suspected bark must be taken and sent to some labora- 
tory for expert judgment. It is absolutely necessary to have arrange- 
ments with some laboratory whereby such work can be done and the 
results promptly reported. 

After the spots already known to exist have been delimited and 
the trees destroyed or marked for destruction, the search should be 
continued. It is best next to clearly define the location of the main 
line of advance of the disease, back of which infection is general. 
Working away from this line as a base, a complete survey of the 
remainder of the State must be made, until it is reasonably certain 
that all spots have been located. 

Scouting is best discontinued as soon as the leaves change color in 
the fall, since from October to April, inclusive, the symptoms are 
very obscure. Practically no sign of the disease is visible from a dis- 
tance, except in those cases where the burs persist on the older trees. 



26 CHESTNUT TREE BLIGHT. 

Even the pustules of the fungus become weathered, so that even a 
close examination of a tree may not yield visible results. But the 
destruction of trees already marked can continue through the winter. 

Destroying advance infections. — Many of the advance infections 
will be found to consist of single trees or of less than half a dozen 
trees. These may perhaps be destroyed by the person who finds them, 
especially if remote from other infections; but the greater part of 
the work of elimination is best handled by other persons under sepa- 
rate direction. Undoubtedly this work can be best directed in each 
State by the State forestry officials. 

The work of elimination should be done as soon as possible after 
the diseased trees are located, but may be done at whatever time of 
year is most convenient, since new infections will be detected by the 
scouting of the following year. The marked trees should be cut 
down. So far as is now known, the timber may be safely utilized in 
various ways, provided it is barked. The bark and brush should be 
piled over the stumps and, as soon as practicable, burned. If it is 
not practicable to have the fire over the stumps, the stumps should 
be barked to the ground; but in any case the bark and brush must 
be burned. 

It will be readily seen that the task of locating the disease, and the 
subsequent one of eliminating it, call for very different talents. The 
"scouting" calls for carefully trained and absolutely accurate scien- 
tific observers working under the most highly specialized direction 
that can be obtained. The work of elimination calls not for scien- 
tific knowledge, but for executive ability, tact in dealing with 
owmers and in otherwise administering the law, and a knowledge of 
forestry and of lumbering, market, and transportation conditions. 
In a word, the first is a task for pathologists, the second for foresters. 
Another advantage of thus dividing the work is that a certain rivalry 
will usually develop, resulting in more thorough work on both sides. 
It is, moreover, of the utmost importance to have as many different 
forces and interests as possible in any given State working toward 
the common end of controlling this disease. 

Establishing the "immvtie zone." — After all advance spots of 
infection are eliminated, attention must be turned to the main fine 
of advance — the edge of the area of general infection. Here the 
problem will present local differences. It may prove necessary in 
some States to destroy all chestnut trees, diseased or healthy, in a 
belt 10 to 20 miles wide, or possibly less. Advantage must be taken 
of natural barriers to infection, such as unforested areas or wooded 
areas without chestnuts. In this way an "immune zone" will be 
established, across which the disease can not easily be transmitted by 
merely local agents. Back of this line the chestnut trees may be 
abandoned to the disease. Every effort should be made, however, to 
have them cut down and the timber utilized as soon as possible, 
since they remain sources of distant infection as long as any spore- 
laden bark or diseased sprouts remain on them. 

Quarantine. — Whether any restrictions are placed upon the move- 
ment of chestnut products from the area of complete infection to the 
protected territory will depend largely on local conditions and must 
be left to the judgment of State authorities. Barked timber can 
probably be moved with comparative safety. It will always be 
desirable to limit the movement of unbarked chestnut timber and fire- 



CHESTNUT TREE BLIGHT. 27 

wood and of chestnut tan bark. An inspection of local conditions 
will readily determine whether the danger from these sources is 
sufficiently great to warrant the business inconvenience which would 
be caused by the quarantine of any or all chestnut products. 

Program for the second year. — The work for the second year will 
consist mostly of reinspection of the advance spots where the bark 
disease has been eradicated the previous year and of general scouting 
to locate new spots. If the work of the first year has been thoroughly 
done and there has been time to complete the elimination of all spots 
located, only scattering infections may be expected. From this time 
on the persons in charge of scouting will have the bulk of work and 
responsibility. 

THE EXAMPLE OF PENNSYLVANIA. 

Pennsylvania enjoys the distinction of being the first and so far the 
only State to undertake in any w T ay the control of the chestnut-bark 
disease. In the summer of 1910 the Main Line Citizens' Associa- 
tion — an organization of citizens residing along the main line of the 
Pennsylvania Railroad near Philadelphia — appointed a committee of 
seven, under the chairmanship of Mr. Harold Peirce, to determine the 
status of the disease in that locality and to see what could be done 
toward controlling it. An extensive local survey of the disease was 
made under the direction of Mr. I. C. Williams, deputy State forest 
commissioner. The committee soon became convinced that the prob- 
lem was of State and even national importance, and could only be 
solved by legislation and by the broadest cooperation. Accordingly 
they devoted their energies to securing the passage by the Pennsyl- 
vania Legislature of the following bill, which has now become a law. 
Tliis law is almost unique in conservational legislation, and on ac- 
count of its important bearing as precedent for similar laws in other 
States it is here reproduced in full. 

AN ACT To provide efficient and practical means for the prevention, control, and eradication of a disease 
affecting chestnut trees, commonly called the chestnut-tiee blight ; providing for the destruction of trees 
so affected; creating a commission to carry out the purpose of this act; fixing penalties for violation of 
the provisions hereof; and making an appropriation therefor. 

Section 1. Be it enacted by the Senate and House of Representatives of the Common- 
wealth of Pennsylvania in General Assembly met; and it is hereby enacted by the authority 
of the same: That a commission to consist of five members, to be appointed by the 
governor for a period of three years from the date of the approval of this act, and to be 
called "The Commission for the Investigation and Control of the Chestnut-Tree 
Blight Disease in Pennsylvania," is hereby created, with power to ascertain, deter- 
mine upon, and adopt the most efficient and practical means for the prevention, con- 
trol, and eradication of a disease of the chestnut tree commonly known as the chestnut- 
tree blight disease; and for this purpose, in collaboration with the depart ment of 
forestry, or otherwise, to conduct scientific investigations into the nature and causes 
of such disease and the means of preventing its introduction, continuance, and spread; 
to establish, regulate, maintain, and enforce quarantine against the introduction and 
spread of such disease; and, from time to time, to adopt and prescribe such regulations 
and methods of procedure as to it may seem necessary and proper for carrying into effect 
the purpose of this act, and exercising the powers and authority hereby conferred: 
J J rovidid, That in the work of collaboration by the commission with the department 
of forestry said department may employ such means, and make detail of such men, 
and do such other things, as may seem to be necessary or expedient to accomplish the 
purpose of this act. 

Sec. 2. Any member of the commission, or any of its duly authorized agents or 
employees, shall have the right, at any time, to enter upon any premises, wild lands, 
farms, fields, private grounds, and inclosures for the purpose of examining into the 
condition of any chestnut tree or trees thereon, and determining whether or not such 



28 CHESTNUT TREE BLIGHT. 

trees, or any of them, have been attacked or infected by the chestnut-tree blight; 
and whenever this disease is found to exist, such commissioners, their duly authorized 
agents and -employees, shall, in all practicable ways, cooperate with the owners of 
such trees in and for the removal, cure, control, and eradication of such disease, and 
the prevention of its spread to other chestnut trees upon adjoining and other properties^ 
shall specifically advise and direct such owner how he shall proceed for the accom- 
plishment of these ends; and shall leave with such owner, his agent, tenant, or other 
representative having charge of such trees, a notice, in writing, containing a descrip- 
tion or plan specifically designating the trees so found to be diseased, and full and 
specific instructions for the treatment of such trees, or for the removal and destruction 
of designated parts thereof, or of an entire tree or trees, as the case may require. 

Sec. 3. If any owner of such trees, so found to be diseased by the said commission, 
its duly authorized agents or employees, shall neglect or refuse to cooperate in applying 
the necessary remedies for the removal, cure, control, and eradication of such disease, 
and the prevention of its spread to other chestnut trees upon adjoining and other 
properties; or shall neglect or refuse to comply with the requirements of the notice 
aforesaid, prescribing the treatment which shall be applied to such trees, so found to 
be diseased, within 20 clays from the time such notice shall have been served, the said 
commission may at once proceed, through its duly authorized agents and employees, 
to do whatever may be found by it to be necessary and proper to accomplish the cure, 
control, or eradication of such disease and the prevention of its spread to other chestnut 
trees; and for this purpose, whenever it may be found necessary may remove, cut 
down, and destroy, or cause to be removed, cut down, or destroyed, any trees or parts 
of trees so found to be infected with such disease; and shall immediately thereafter 
duly certify to the owner of such trees, so treated or destroyed, or to his tenant, agent, 
or other representative in charge of such trees, the amount of the cost or expenses 
actually incurred by the commission in the treatment, removal, or destruction of such 
trees; and if the amount of such expense, so certified, shall not be paid by such owner 
of said trees, so treated, removed, or destroyed, within 60 days after it shall have been 
so certified, the same may be recovered by the said commission, from such owner, 
by an action in the name of the Commonwealth, in the same manner as debts of like 
amount are now recoverable, and when recovered may be used by said commission 
in carrying out the purposes of this act. 

Provided, however, That any owner or owners of trees, his or their tenants, agents, 
or representatives, who may be dissatisfied with any decision, order, or notice of any 
member of the commission, or any of its agents or employees, directing or prescribing 
the treatment, removal, or destruction of trees belonging to or controlled by them, 
shall have the right within 10 days from the time of the service upon them of such 
order or notice to appeal therefrom, in writing, to the commission, which shall there- 
upon, without avoidable delay, direct a reexamination of the premises or trees in 
question, by competent experts, who shall make report of their findings to the com- 
mission; which shall then fix a time and a place for a hearing before it, upon such 
appeal, and notify the person making appeal thereof. All further proceedings under 
such order or nol ice shall be suspended until the decision of the commission shall have 
been formally rendered. 

Sec. 4. Whenever, in the judgment of the commission, it may be necessary to dest r< >y 
chestnut trees not affected by the chestnut-tree blight, for the purpose of establishing 
a quarantine to prevent and control the spread of the disease, the owner of such trees 
shall be reimbursed for the loss of all the good and unaffected trees so destroyed; the 
amount to be paid therefor to be not greater than the stumpage prices of such trees, 
prevailing at the time in the locality where such trees grew; such value to be deter- 
mined by the commission, by such method or procedure as it may adopt, and payment 
therefor to be made from the fund hereinafter specifically appropriated for the use of 
the said commission in performing the duties required by this act. Should any owner 
of trees be dissatisfied with the amount awarded to pay for the destruction of such good 
and unaffected trees, said owner shall have all the remedies now existing, or which 
may hereafter be provided by law, for the protection of his interests. 

Sec 5. Any person who shall willfully violate any of the provisions of this act, or 
any of the regulations of the commission intended to assist m carrying this act into 
effect, or shall willfully resist or interfere with any agent or employee of the said com- 
mission in the performance of his duties in accordance with the regulations and orders 
of the commission, under the provisions hereof, shall be deemed guilty of misdemeanor, 
and shall upon conviction thereof be punished by a fine not exceeding $100, or by 
imprisonment not exceeding one month, either or both, at the discretion of the court. 
The word "person," as used in this act, shall include not only individuals or natural 
persons, but as well artificial persons, existing only in contemplation of law, and shall 
be construed to mean partnerships, limited partnerships, joint-stock companies, and 
corporations, and the officers, agents, and employees of the same. 



CHESTNUT TREE BLIGHT. 29 

Sec. 0. The members of the commission shall serve without pay, but shall be reim- 
bursed for all actual expense incurred by them in exercising the powers conferred 
upon them and performing the duties required by this act. The employees of the 

commission shall receive such compensation for their services as the <■ dssioil shall 

determine will fairly compensate them for the work to he dune. The commission 
shall he furnished with suitable rooms in the Capitol building at Earrisburg, or else- 
where, by the Superintendent of Public Grounds and Buildings. The sum of $25,000 
is hereby specifically appropriated, to be immediately available upon the; approval 
of this act, for the payment of such expense as may be incurred by the commission, for 
such scientific research and for office expenses, as in their judgment may lie necessary 
to comply with the provisions hereof, said appropriation to he available until the 1st, 
day of June, A. D. 1913; and the further sum of $250,000, or so much thereof as shall 
be necessary, is hereby specifically appropriated, to be available only upon the 
approval of the governor, for the performance of all other duties herein required to 
be done; as, for quarantine, removal of diseased trees or other trees, conducting out- 
side investigations and operations, and every other means of eradication and control, 
as to it may seem necessary in complying with the provisions hereof. 

Sec. 7. All acts or parts of acts inconsistent herewith are hereby repealed. 

The commission authorized by the bill has been appointed by the 
governor of Pennsylvania and consists of the following persons: 
Mr. Winthrop Sargent, chairman; Mr. Harold Peirce, secretary; 
Messrs. Samuel T. Bodine, George F. Craig, and Theodore N. Ely. 
Persons desiring information regarding the work on tins disease in 
Pennsylvania should address the executive officer of the commission, 
Mr. Samuel B. Detweiler, 1112 Morris Building, Philadelphia, Pa. 

INSPECTION OF DISEASED NURSERY STOCK. 

As has been indicated, diseased chestnut nursery stock has in the 
past been a most important factor in the spread of the bark disease. 
On account of a well-grounded fear of this disease much less nursery 
stock is being moved now than formerly, but there is still enough to 
constitute a serious source of danger. It is therefore obvious that 
every State in which the chestnut grows, either naturally or under 
cultivation, should as speedily as possible pass a law putting the 
chestnut bark disease on the same footing as other pernicious diseases 
and insect pests, such as peach yellows and the San Jose scale, against 
which quarantine measures are taken. Many inspectors already have 
legal power to quarantine against the bark disease on chestnut nurs- 
ery stock, and they should now take special care that no shipment, 
however small, escapes their rigid inspection. 

The most serious practical difficulty in inspecting nursery stock for 
tins as for other fungous diseases lies in the fact that practically all 
State inspectors are necessarily entomologists, and are not trained in 
recognizing the more obscure symptoms of fungous diseases. Nursery 
trees affected by the bark disease rarely show it prominently at the 
time when shipped; the threads of summer spores or the yellow or 
orange pustules are rarely present, and usually all the inspector can 
find is a small, slightly depressed, dark-colored area of dead bark, 
usually near the ground, wnich is easily overlooked or mistaken for 
some insignificant injury. Upon cutting into such a spot, the inner 
bark shows a most characteristic disorganized "punky appearance, 
quite different from that of any other bark injury; but it is impos- 
sible to adequately describe this appearance without recourse to 
colored illustrations. Occasionally a yellowish-brown band, either 
girdling or partly girdling the young tree, may be seen; this is very 
characteristic, but is so prominent a symptom that it may be noticed 
at the nursery, and presumably trees so affected will not be shipped. 



30 CHESTNUT TREE BLIGHT. 

If infected trees are set out they develop the disease with its char- 
acteristic symptoms the following spring. But on account of their 
small size such trees are girdled and die before the end of the sum- 
mer, often in two or three weeks. Meanwhile they are spreading 
the disease to neighboring orchard and forest trees. Orchardists 
and nurserymen purchasing chestnut trees are therefore warned to 
watch them closely during the first season, no matter how rigidly 
they may have been inspected. 

INDIVIDUAL TREATMENT OF DISEASED TREES. 

Where valuable ornamental, shade, or orchard chestnut trees be- 
come infected in one or more spots, the life and usefulness of such 
trees can be prolonged for several or for many years, depending 
largely upon the thoroughness with which the recommendations 
herein given for cutting out the diseased areas (lesions) are carried 
out. These recommendations are based upon the results of extensive 
experiments with hundreds of lesions during the past four years. 
These experiments were performed for the most part by the junior 
writer. 

The essentials for the work are a gouge, a mallet, a pruning knife, 
a pot of coal tar, and a paint brush. In the case of a tall tree a 
ladder or rope, or both, may be necessary, but under no circum- 
stances should tree climbers be used, as they cause wounds which 
are very favorable places for infection. Sometimes an ax, a saw, 
and a long-handled tree pruner are convenient auxiliary instruments, 
though practically all the cutting recommended can be done with a 
gouge with a cutting edge of 1 or 1J inches. All cutting instruments 
should be kept very sharp, so that a clean and smooth cut may be 
made at all times. 

By cutting with the gouge into a diseased area a characteristically 
discolored and mottled middle and inner bark is revealed. All of 
this diseased bark should be carefully cut out for at least an inch 
beyond the discolored area if the size of the branch will allow it. 
Tliis bark should be collected in a bag or basket and burned. If the 
cutting is likely to result in the removal of the bark for much more 
than half the circumference of the branch or trunk, it will probably 
be better to cut off the entire limb or to cut down the tree, as the 
case may be, unless there is some special reason for attempting to 
save the limb or tree. The fungus usually, though not always, de- 
velops most vigorously in the inner bark next to the wood. When 
this is the case, not only all the diseased bark and an inch of healthy 
bark around it must be removed, but at least two or three annual 
layers of wood beneath the diseased bark must also be gouged out. 
Special care should be taken to avoid loosening the healthy bark at 
the edges of the cut-out areas. Except in the early spring this is 
not difficult after a little experience in manipulating the gouge and 
mallet, provided the gouge is kept sharp. 

Small branches which have become infected should be cut off, the 
cut being made wel 1 back of the disease — at least 2 or 3 inches, if 
possible. 

All cut-out areas and all the cut ends of stubs should be carefully 
and completely painted with coal tar. A good grade of paint has 



CHESTNUT TREE BLIGHT. 31 

been recommended by some authorities as superior to tar, but it is 
more expensive. If the tar is very thick, the addition of a little creo- 
sote will improve it for antiseptic purposes as well as for ease in 
applying. If the first coat is thin, a second one of fairly thick tar 
should be applied within a few weeks or months. Other coats should 
be applied later whenever it becomes necessary. 

The entire tree should be carefully examined for diseased spots and 
every one thoroughly cut out and treated in the way already de- 
scribed. In case of suspicious-looking spots a portion of the outer 
baric can be cut out with the sharp gouge as a test. If this cut shows 
the characteristically discolored bark the spot can be considered as 
diseased and cut out accordingly; if the cut shows healthy bark, it 
need merely be treated with tar or paint, as other cuts are treated. 
In examining a tree for diseased spots it is always best to begin at 
the base of the trunk and work up, for if the trunk is girdled at the 
base it is useless to work anywhere on the tree. 

When the spores of the fungus are present, especially in the form 
of threads, or- "horns," they are readily washed down the branches 
and trunk by every rain, and are thus carried down to or toward 
the base of the tree. As a result the base of a tree, the crotches, and 
other places which afford easy lodgment for the spores are particu- 
larly subject to infection. 

Although spraying with airy of the standard fungicides appears 
to have no effect whatever in stopping the progress of the disease 
after it has once started in the inner or middle bark, there is little 
doubt that it is of use in preventing infection from spores washed 
down by rain from the upper part of a tree or from spores winch 
have been transported from other trees. For this reason the spray- 
ing, after each rain, of the parts of a tree below a spore-bearing 
lesion is recommended, but only on an experimental basis. If no 
spore-bearing lesions occur on the tree, there is less apparent reason 
for spraying. The scattering of slaked lime about the base of a tree 
and the whitewashing of the trunk and larger limbs have shown 
apparently beneficial results in preventing infections and perhaps 
also depredations of borers. 

A tree which is being treated for individual infections must be 
carefully watched and the diseased spots promptly cut out as they 
appear. For this purpose each tree should be examined very care- 
fully two or three times at least during the growing season. 

The Department of Agriculture asks the cooperation of all persons 
who have experimented with the disease in any way, and in return 
is ready to give specific advice, based upon extensive experience with 
the disease, as to the best methods of attempting its control or as to 
what are likely to be the most profitable systematic observations or 
experiments. 

ADVICE TO CHESTNUT ORCHARDISTS. 

In view of the uncertain future of the chestnut tree, the Depart- 
ment of xigriculture advisos against planting chestnuts anywhere east 
of Ohio, at least until it is settled what efforts will be made by the 
individual States to control the bark disease. The only exception is 
that Japanese chestnuts may be grown if raised from imported seeds 
and not grafted on American stocks. If the seed is raised in America, 



32 CHESTNUT TREE BLIGHT. 

the trees are more than likely to be hybrids with the American chest- 
nut and to vary greatly in resistance to the bark disease. If grafted 
on American stocks, the stocks readily succumb to the disease, and 
so the whole tree is killed, no matter how resistant the scion. may be. 
However, the nut of the true Japanese chestnut is of poor quality at 
best, and it is an open question whether it can ever be made a com- 
mercial success. 

West of the natural range of the American chestnut, however, the 
situation is quite different. Obviously the western chestnut orchard- 
ist has before him a great opportunity. No matter how successful 
efforts to limit the bark disease in the East may be, the nut crop will 
be reduced for some years, and the business of growing fine orchard 
chestnuts in the East will be depressed for the same length of time. 
There is no apparent reason why, with rigid inspection, both of any 
purchased stock and of the orchards themselves, all chestnut orchards 
and nurseries from Ohio to the Pacific coast can not be kept perma- 
nently free from the bark disease ; therefore all persons interested in 
growing the chestnut in the West as an orchard tree are earnestly 
advised not to secure any chestnut nursery stock from eastern nur- 
series; to be sure that stock from any source is rigidly inspected; to 
watch with the utmost care their own nurseries and orchards; 'and to 
destroy immediately by fire any trees that may be found diseased. 

There is presumptive evidence that the bark disease was introduced 
into America on the Japanese chestnut, but until this point is defi- 
nitely settled orchardists west of Ohio are advised not to import nur- 
sery stock of this variety. Seed can probably be imported with a 
reasonable degree of safety, however. 

ADVICE TO OWNERS OF CHESTNUT WOODLAND. 

Owners of chestnut woodland anywhere within the area of com- 
plete infection are earnestly advised to convert their trees into lumber 
as quickly as possible. The trees that are not already killed will soon 
die in any case and the timber will quickly deteriorate in quality. 
Such trees are a continual source of further infection, and, moreover, 
large areas of dead chestnut trees, by harboring bark and wood 
inhabiting insects, are likely to start some insect epidemic. ^ Indeed, 
with the quantity of dead chestnut timber now standing it will be 
remarkable if some serious infestation of insects extending to sound 
trees does not follow. 

Owners of chestnut woodland outside the area of general infection 
are counseled to watch for the first appearance of the disease, and 
when it appears to cut down immediately all affected trees, bark 
them, and burn the bark and brush, over the stump if practicable. 
Such procedure will distinctly retard the spread of the disease^ in 
that particular woodland, even if no concerted efforts at elimination 
are made by neighboring owners. It is to be expected, however, that 
in all cases of this land the owner will have the cooperation of the 
State authorities in a general quarantine movement. 

It is almost needless to add that until we know what action is to 
be taken in all the chestnut-growing States and what the results are 
likely to be, chestnut woodland is a poor investment. Furthermore, 
in forest management, as in improvement cuttings, etc., there should 
be discrimination against the chestnut. 



CHESTNUT TREE BLIGHT. 33 

ADVICE TO OWNERS OF ORNAMENTAL CHESTNUT TREES. 

Until the future of the chestnut tree is better known, or at least 
until we know what legalized action is going to be taken in the 
States concerned, the owners of chestnut-timbered land available for 
building should pursue a very conservative policy. Houses should 
not be located with sole reference to chestnut groves or to isolated 
ornamental chestnut trees. Houses so located should he discrimi- 
nated against in purchasing homes in so far as the death of the 
chestnut trees would injure the appearance of the place. 

When ornamental trees become diseased they had better be cut 
down at once and, if practicable, large trees of other species moved 
in to take their places. In expert hands the moving of large trees is 
a perfectly practicable and successful procedure and, although more 
expensive, is much more satisfactory than waiting for nursery trees to 
grow. 1 

All owners of diseased ornamental chestnut trees are specifically 
warned against "fake" tree doctors. Large sums of money have 
been paid out in many cases for treatment that has been worse than 
useless. Reliable tree specialists will have nothing to do with trees 
affected with the chestnut bark disease, or, if they do anything, do it 
with the distinct understanding in advance that it is entirely at the 
owner's risk. Of course, if an owner desires to employ tree surgeons 
to experiment, that is another matter. 

ADVANCING POPULAR KNOWLEDGE OF THE DISEASE. 

In the localities where infection is general or complete (fig. 2) 
everyone knows what the chestnut bark disease is and what its symp- 
toms are and everyone appreciates its seriousness; but in these local- 
ities it is too late even to attempt its control. On the other hand, in 
Delaware, Virginia, West Virginia, western and southern Mary- 
land, western Pennsylvania, central and northern New York, Massa- 
chusetts, and Rhode Island very few people know the symptoms of 
the disease. On this account no one notices it until it is thoroughly 
established, and by the time public sentiment is sufficiently aroused 
to authorize the necessary legislation and bring about united action 
for public protection it is too late for such action to be of service. 
Obviously, then, every effort should be made by all State and other 
officials having such matters in charge to acquaint every citizen with 
the prominent symptoms of the bark disease and to familiarize him 
with the fact that unless prompt and united action is taken there 
is every indication that the chestnut tree in the States above men- 
tioned will become practically extinct within 10 years. 

COOPERATION OF THE DEPARTMENT OF AGRICULTURE. 

In this campaign of education the Department of Agriculture will 
cooperate in the following ways: Copies of this bulletin or of other 
publications of this department relating to the bark disease, and also 

1 In case such action is not immediately durable or possible, a very good, though temporary, scenic 
effect can be obtained by lopping off the end-; of the larger branches of the dead and dying chestnut trees', 
removing the bark, and planting some rapid-growing vine at their foot, which soon covers them. One 
of the best for this purpose is the Japanese kudzu vine (Pueraria thumbergiana (S. and Z.) (Bcnth.). on 
account of its extraordinarily rapid growth. Such vine-covered stumps must be carefully watched, how- 
ever, for in a very few years they decay and are liable to be blown over. 

43017°— S. Doc. 653, 62-2 3 



34 CHESTNUT TREE BLIGHT. 

typical specimens of the disease, will be sent to any person applying 
for them. Two specimens will be sent to each person — one snowing 
the appearance of the disease on smooth bark, and the other the later 
development of the fungus on thick bark. In both these specimens 
the fungus will have been killed by soaking in formalin to insure 
against any infection from this source. 

So far as the supply permits, lantern slides and photographs will, 
upon application, be loaned for special lectures, exhibits, etc., to the 
officers of States, experiment stations, colleges, and schools where 
agriculture is taught, as well as to tree wardens and other officials 
whose work may bear directly upon local campaigns of publicity. 

Tins department will always examine any suspected specimens of 
this disease sent to Washington by mail, and will report the findings 
as promptly as possible. Before sending specimens, however, all 
persons are urged to read the paragraphs on symptoms on pages 6 to 
9 in order to select the specimens intelligently. For example, if the 
end of a girdled and withered branch is sent, it is not possible to make 
a dependable diagnosis unless a portion of the girdling area happens 
to be included. This is the only part where the fungus is surely 
present, and the fungus iteslf must be seen in order to be absolutely 
sure of the disease. Portions of the bark that show the small orange 
or reddish-brown pustules, about the size of the head of a pin, should 
always be sent , if these can be found. These commonly occur near the 
lower edge of the girdling area. 

PUBLIC COOPERATION. 

With many people familiarized with the appearance of the chest- 
nut-bark disease and its possibilities of harm, the disease will be 
noticed and stamped out by private effort in man}' places when it 
first appears and the public will understand and be ready to cooper- 
ate in any official measures of control as soon as these become neces- 
sary in any locality. 

All possible forces must be enlisted in a campaign of publicity. 
The cooperation of all newspapers, particularly local papers, can be 
easily secured in all the States where the chestnut is an important 
tree. A portion of the program for Arbor Day, 1912, should be 
devoted to a consideration of tins disease. Teachers of nature study, 
botany, or agriculture in the public schools can do great service by 
teaching their pupils how to recognize the disease and by training 
them to be on the lookout for its first appearance in the home com- 
munity. Such a body as the "Boy Scouts" can, if properly trained, 
become in eveiy community a most efficient force for locating the 
disease. The boys will readily appreciate that such work is real 
"scouting" against a most insidious and destructive public enemy. 
And, finally, many private owners of chestnut trees wall be eager to 
cooperate with the State authorities in the early elimination of 
advance infections if only they are able to recognize such infections. 

THE PROTECTION OF THE SOUTHERN STATES. 

It must be remembered that the bark disease has as yet done only a 
small fraction of the damage that it is undoubtedly capable of doing. 
The best chestnut timber of America is south of the Potomac Iliver 



CHESTNUT TEEE BLIGHT. 35 

and there the Dark disease is present in only a few spots. For this 
reason it is of extraordinary importance that these few spots be eradi- 
cated and that the disease be soon controlled immediately north of 
the Potomac. If the bark disease once becomes well established in the 
chestnut forests of the South, it will be well-nigh impossible to control 
it, on account of the sparsely settled and mountainous condition of 
much of that country and for other reasons which do not obtain 
farther north. 

SUMMARY. 

(1) The chestnut-bark disease was first noted near New York 
City in 1904 and is now present in at least 10 States. It attacks the 
American chestnut, the European chestnut, the chinquapin, and, 
rarely, the Japanese chestnut. 

(2) The total financial loss from this disease is now estimated at 
$25,000,000. 

(3) The disease is caused by a fungus, and the entrance of a spore 
at any point where the bark is broken may cause infection. The 
disease spreads primarily in the inner bark and produces character- 
istic lesions which girdle the tree at the point attacked. 

(4) Conspicuous symptoms are the development of bunches of 
sprouts below the girdling lesions; the half-formed yellowish leaves 
in the spring on the previously girdled branches, the reddish-brown 
leaves on branches girdled in summer, and the yellow, orange, or 
reddish-brown pustules of the fruiting fungus on the bark. It is 
practically useless to attempt systematic location of the disease from 
October to April, inclusive. 

(5) The spores may be carried considerable distances on chestnut 
nursery stock, tan bark, and unbarked timber; also by birds, insects, 
squirrels, etc., which have come in contact with the sticky spore 
masses. Water quickly dissolves these spore masses and the minute 
spores are in this way carried along with water, as, for instance, with 
rain water running down a tree. Borers' tunnels form the most 
common places of entrance for spores. 

(6) The only known practical way of controlling the disease in 
a forest is to locate and destroy the advance infections as soon as 
possible after they appear and, if the disease is well established near 
by, to separate the area of complete infection from the comparatively 
uninfected area by an immune zone. Advance infections should be 
located by trained observers and destroyed by cutting and burning. 
As the disease develops almost entirely in the bark, this must be com- 
pletely destroyed (burned). 

(7) In order to carry out the above methods it is essential that 
the several States concerned secure necessary legislation and appro- 
priations, following the example of Pennsylvania, as no law exists 
whereby the Federal Government can* undertake such work and 
cooperation among private owners without State supervision is 
impracticable. 

(8) Chestnut nursery stock should be rigidly inspected for the 
disease and only perfectly healthy plants passed. 

(9) The life of valuable ornamental trees may be greatly prolonged 
by promptly cutting out all diseased areas and removing all disease- 
girdled branches and then covering the cuts with tar. Spraying is 



36 CHESTNUT TREE BLIGHT. 

of no use in stopping the fungus after it has once started growth in 
the bark. 

(10) It is recommended that owners of infected woodland cut 
down and utilize the diseased chestnut timber as soon as possible. 

(11) For the present the planting of chestnuts anywhere east of 
Ohio is not advised, but there is no apparent reason why chestnut 
orchards west of Ohio may not be kept free from the disease. 

o 



Senate Document No. 653, 62-2. 



Plate I. 




Known Distribution of the Chestnut Bark Disease February 1, 1912. 

[Horizontal lines show the botanical distribution of the American chestnut tree. Dots repre- 
sent advance infections. Thicker lines, arranged concentrically about New York City, 
show various degrees of general infection and death.] 



Senate Document No. 653, 62-2. 



Plate II. 




Fig. 1.— Typical Group of Large Chestnut Trees Dying with the Bark 
Disease. Near Brookville, N. Y. 

[Note appearance of foliage.] 




Fig. 2.— Dead Chestnut Trees Along a Boulevard, near Richmond Hill, 

N. Y. 

[Note healthy condition of trees of other species. J 



Senate Document No. 653, 62 



Plate III. 




Fig. 1.— The most Southern Point of Infection— A Group of Diseased 
Chestnut Trees at Fontella, Bedford County, Va. 



























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Fig. 2.— Forest Tree Nearly Dead. Parkton, Md. 
[Note characteristic sprouts and dwarfed leaves of the only surviving branches.] 



Senate Document No. 653, 62-2. 



Plate IV. 



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Fig. 1.— Tree with some Large Branches Girdled, Westbury, N. Y. 
[Note appearance of foliage.] 




Fig. 2.— Tree with Small Branches Girdled, Buck, Pa. 
[Note appearance of foliage.] 



Senate Document No. 653, fi2-2. 



Plate V. 





Complete Destruction of Chestnut Trees in Mixed Stand. 
[Note health j- condition of trees of other species. Views along the Long Island Railroad.] 



Senate Document No. £53, 62-2. 



Plate VI. 




Fig. 1.— Complete Destruction of Chestnut Trees in Nearly Pure Stand. 
[Many of the trunks have been dead long enough to shed their bark. Near Brooklyn, N. Y.] 




Fig. 2.— Complete Destruction of Chestnut Trees in a Nearly Pure Stand. 
[Xote healthy condition of other species. Forest Park, near Brooklyn, N. Y.] 



Senate Document No. 653, 62-2 

IE 



Plate VI 




Senate Document No. 653, 62-2. 



Plate VI If. 





Grafted Varieties of Orchard Chestnuts, Nearly Dead. Martic Forge, Pa. 
[Note the suckers on the trunk and the appearance of the foliage.] 



Senate Document No. 653, 62-2. 



Plate IX. 







Mi- ... .J Wfe^^ 



; 'l '-.^"iV'l iiiiw? 



Fig. 1.— Early Stage of Disease. Infection of a Small Branch in the Top 
of the Tree. Westbury, N. Y. 




Fig. 2. 



-Early Stage of Disease. End of Branch Girdled at Upper Right- 
Hand of Picture. Lancaster County, Pa. 



Senate Document No. 653, 62-2. 



Plate X. 





co >- 



Senate Document No. 653, 62-2. 



Plate XI. 




^H^' 




% ■ % 



Dead Chestnut Trees, with Bark in Successive Stages of Decay, Showing 
Pustules of the Fungus in which the Winter Spores are Borne. 



Senate Document No. 653, 62-2. 



Plate XII 





Late Stages of Decay of Bark and Outer Layers of Wood. 



Senate Document No. 653. 62-2. 



Plate XIII. 




Fig. 1.— Dead and Dying Sprout Growth, Port Jefferson N. Y. 

[Note healthy condition of trees of other species.] 




Fig. 2.— Typical Group of Dead Chestnut Trees. Near Brooklyn, N. Y. 

[Note dead suckers on the trunks. From left to right: The first trunk shows the disease 
less than 1 year old: the second from 2 to 3 years old; the third 4 or more years old; 
and the fourth about 3 years old.] 



Senate Document No. 653, 62-2. 



Plate XIV. 




Fig. 1.— External Appearance of a Young Lesion of the Chestnut Bark 
Disease, Showing the Spread of the Disease from an Insect Puncture. 




Fig. 2.— The Same as Fig. 1, with the Outer Bark Removed to Show the 
Centrifugal Spread of the Mycelium of the Parasitic Fungus. 



Senate Document No. 653, 62-2. 



Plate XV, 




Small Chestnut Tree in Pot about 3 Months after Artificial Inoculation with 
Summer Spores from a Pure Culture of the Fungous Parasite. Tree Girdled 
at Base, Leaves above Withered; Vigorous Suckers Growing Uf from Below 
Girdled Point. 



Senate Document No. 653, 62-2. 




Plate XVI. 


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Examples of Tree Surgery, Showing Healing Processes after Cutting 
Out Lesions, in Treatment of Orchard Trees. 



Senate Document No. 653, 62-2. 



Plate XVII. 




Fig. 1. -Large Chestnut Tree Killed by the Bark Disease. 




Fig. 2.— An Orchard Tree, Showing Recently Girdled Branches. 




Fig. 3.— Part of a Diseased Branch of a Chestnut Tree, Showing 
Typical Pustules and Form of Spore Discharge in Damp Weather. 

[Magnified 3 diameters.] 



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